Method of making an inflatable rubber structure



Aug- 21, 1 J. H. JOHNSON MFPHOD OF MAKING AN INFLATABLE RUBBER STRUCTURE Filed Oct. 3, 1952 Patented Aug. 21, 1934 METHOD or MAKING AN INFLATABLE PATENT orrlca S RUBBER STRUCTURE John Herbert Johnson, Toronto, Ontario, Canada Application October 3, 1932, Serial No. 636,086 3 Claims. (01. 154-2) The principal object of this invention is to provide a form of inflatablerubber goods, the in terior 01' which will be sub-divided into a ,plurality of individual air chambers, each of which may be inflated to a particular pressure in accordance with requirements and in the provision of means for controlling the expansion of the air chambers. I

A further and important object is tosimplify the-production of a product of this nature and to provide an integral structure throughout.

\The principalfeature of this invention consists in the hovel construction and method of fabricating wherein the extensible side walls of the inflatable device have permanently united therewithjduring the vulcanizable process, extensible rubber strips which serve to subdivide the interior into a plurality of separate compartments and which serve to control the outward flexing of the sides.

In the drawing, Figure 1 is a plan view of an inflatable unit constructed in accordance with this invention and showing the central portion broken away.

Figure 2 is a cross section on an enlarged scale through a portion of the structure shown in Figure 1.

Figure 3 is an enlarged detail sectional view illustrating the disposition of the extensible partition element. and the manner of fabricating.

Figure 4 is a sectional perspective view of a mattress illustrating the present invention applied thereto. T

Figure 5 is an elevational part sectional view of a mattress shown in Figure 4 showing the disposition of the elements in their inflated form.

Figure 6 illustrates a modified form of construction.

Rapid progress has been made recently in the production of inflatable rubber goods.

The present invention proposes a distinct advance over what has been done heretofore and it is a purpose of the present invention to overi come objections associated with former structures and to enable the economic production of a cushioning element or the like which may carry different pressures of inflation at various points within its interior and which will not be subject ""to undesired lateral. expansion, permitting the retention of higher pressures than heretofore. In the form'of construction illustrated in the drawing, a pair of rubber'sheets 1 and 2 are a first provided of the desired shape and size, such sheets being in unvulcanized form and between these sheets are placed a plurality of paper sheets 3 corresponding to the number oi compartments it is desired to form. The dimensions of these sheets are such that they permit the outer edge portions of the rubber sheets to contact with each other and they are preferably perforated at a plurality of points-to permit contact of the rubber sheets during subsequent vulcanizing at" the points 4. g

Strips 5 of unvulcanized rubber are doubled intermediate of their width and inserted between the rubber sheets 1 and 2 in the manner illustrated in Figure 3, these stripsbeing preferably placed to conform to the dotted line indication of Figurel, t.

The paper strip 3 as shown extends into the apex of the doubled strip 5 and thus serves to prevent surface contact of the opposing portions of the 'strips 5. w

Strips of paper 6 are doubled intermediate of their width and placed as indicated in Figure 3 so that the respective free portions thereof extend between thesheets 1 and 2 andthe adjacent convergent sides of the doubled rubber strip 5. The strips 6 are so placed that the edge extremities '7 thereof terminates at a point from the so edge extremities 8 of the doubled rubber strip-5 so that the longitudinal edge portion of the strips 5 not covered by the paper strip 6, is permitted to contact with the overlying rubber sheets 1 and 2.

It will thus be seen that by applying pressure and vulcanizing temperature to the composite structure thus produced that the outer sheets 1 and 2 will be permanently united at all points where they are permitted to come into contact, and that the doubled rubber strips 5 will also become integrally united at their points of contact with the rubber sheets 1 and 2 so that'the interior of the resultant product will be very positively sub-divided into separate, air-tight compartments.

It will be further noted that the presence of the doubled rubber partition strips 5 in the completed structure, will serve not only to sub-divide the interior into the desired compartments, but its presence will eifect a very definite control of the expansion of such chambers when inflated as will be apparent on reference to Figure 5.

Each of the interior compartments thus provided is preferably provided with a valve inlet 9 extending through the projecting lug formation 10 of the sheets 1 and 2.

Thus, when the structure described is applied to a mattress as illustrated in Figures 4 and 5, a very accurate control of the inflation and cushioning properties is provided for, and where a tendency for the mattress to sag in the middle. is encountered, as is frequently the case, the central compartment is simply inflated to a greater degree than the outer compartments and a similar control can be eifected where persons of greatly diflfering weights are obliged to lie on the same mattress. In the form of construction illustrated, in Fi ure 6, a pair of rectangular strips of paper 11 are placed in juxta-position between the two outer rubber sheets and a plurality of doubled rubber strips 5 are placed in a rectangular arrangement in spaced relation to the sides and ends of the outer rubber sheets, the apex of these doubled rubber strips being disposed outwardly and the paper strips 11 are of such a width that the inner edge 12 thereof terminates a short distance from the inner edge 13 of the doubled rubber strips 5'.

A- strip of paper 1'1 of rectangular form is also placed between the outer rubber sheets and centrally thereof so that its outer edges 18 extend between the doubled rubber strips and into the inner apex thereof so that only the outer portions of the doubled rubber strips adjacent the longitudinal edges 12 are permitted to contact with the outer rubber sheets so that they will be permanently vulcanized at this point to the outer sheets in the subsequent vulcanizing operation.

It will thus be seen that with this construction, when the deviceis inflated the lateral pressure on the side walls will extend the doubled rubber strips drawing outwardly on the connected' edge portions 16 so that the apex portions thereof will move inwardly as the strips 5' straighten out, thus closing together at the corners and forming a distinct air chamber centrally of the device. The formation of a separate air chamber in this manner prevents rapid displacement of the air from one section to the other when pressure is applied to one part such as is occasioned when the device is used as a cushion and the presence of the connecting strips 5 will inhibit the undesired tendency of a device of this nature to roll or become unsteady when weight is applied.

It will be readily appreciated that many variations may be made in the actual construction while still remaining within the scope of the invention.

What I claim as my invention is:-

l. A method of producing inflatable rubber goods comprising placing a plurality of preformed unvulcanized rubber sheets in juxtaposed relation, placing a plurality of doubled partition strips of unvulcanized rubber between said sheets, placing separating strips of paper between said sheets arranging same to overlie the doubled strips on their opposite outer sides leaving marginal edge portions of the sheets and strips exposed for direct inter-contact, placing second strips of paper between said sheets on the opposite side of the doubled strip and arranging same to extend between the doubled portions of the rubber strips with the first-mentioned paper strips disposed in overlapped relation thereto, and applying heat and pressure to vulcanize the composite structure and permanently unite the intercontacting surfaces.

2. A method of producing inflatable rubber goods comprising placing a plurality of preformed unvulcanized rubber sheets in juxtaposed relation, doubling a plurality of strips of unvulcanized rubber longitudinally, placing said doubled strips between the juxtaposed sheets in a substantially rectangular arrangement with the apex portion of the doubled strips disposed outwardly in the direction of the marginal edges of the sheets and with the free edges thereof substantially clear of each other, interposing sheets of paper between the rubber sheets to extend to the outer sides of each of the doubled strips leaving the inner longitudinal free edges of the latter free to contact with the sheets and leaving the outer marginal edges of the sheets free to contact with each other, placing a separate sheet of paper between the sheets to extend between the doubled strips, and applying heat and pressure to integrally unite the composite structure at the points of contact of said sheets and strips.

3. An improved method of producing inflatable rubber goods of the type in which superposed outer sheets are sealed together at the edges and the interior space is subdivided by a plurality of partition strips permanently united along their marginal edges to the sheets, comprising the step of associating with each rubber strip a set of paper separating sheets, placing said separating sheets between the rubber sheets on opposite sides of the rubber strip with the rubber strip interposed therebetween and with the marginal edge portions of the paper sheets of each set overlapping each other a distance less than the width of the interposed rubber strip, ,then vulcanizing under pressure.

JOHN HERBERT JOHNSON. 

